Heat sealing thermoplastic packages



July 13, 1965 J. BADER HEAT SEALING THERMOPLASTIC PACKAGES 4Sheets-Sheet 1 Filed Jan. 22, 1962 INVENTOR. J M BADER goh l; fz!

ATTORNEYS July 13, 1965 J. BADER v 3,193,978

HEAT SEALING THERMOPLASTIC PACKAGES Filed Jan. 22, 1962 4 Sheets-Sheet 2INVENTOR. J. M. BADER MM I A TTORNEVS July 13, 1965 Filed Jan. 22. 19624 Sheets-Sheet I5 INVENTOR. J. M. BADER ATTORNEYS July 13, 1965 J. BADERHEAT SEALING THERMOPLASTIC PACKAGES 4 Sheecs-Sheetl 4 Filed Jan. 22,1962 INVENTOR. J. M. BADER ATTORNEYS United States Patent() 3,193,978HEAT SEAMNG THERMPLASTIC PAEKAGES Julius Bader, Mountainside, N..assigner to Phillips Petroleum Company, a corporation oi Deiaware FiledSian. 22, 1962, Ser. No. 167,635 16 G'Jlaims. (Ci. 5.3-1.4)

This invention relates to heat sealing thermoplastic members. In oneaspect the invention relates to a method for sealing thermoplasticpackages utilizing a plurality of heat sources which move parallel withand synchronized with the packages to be sealed through a sealing zone,moving the sealing elements into engagement with corresponding packagesto be sealed, removing the elements from contact with the packages andreturning them as a unit in the opposite direction to their initialposition. In another aspect this invention relates to an improvedpackaging machine which conveys packages to be sealed along apredetermined path parallel with and synchronized with heat-sealingelements which are moved into heat-sealing engagement, following whichthe heat-sealing elements are moved out of engagement as a unit and theentire group moved together in the direction opposite to the movement ofthe packages to their initial position. In another aspect this inventionrelates to a method for applying sealing covers to packages includingthe steps of providing a plurality of longitudinally-spaced, parallelpairs of slits, -attaching a continuous tear strip to the sheet byheating and pressing the strip to the sheet longitudinally thereofbetween the slits, and cutting the sheets transversely at each pair ofslits thereby forming individual covers having tear strips and startingtabs. In another aspect this invention relates -to means for makingcovers for thermoplastic packages and applying the covers to thepackages, including means for forming a plurality of pairs of parallelslits, each pair longitudinally spaced along the sheet, means to seal acontinuous tear strip to the sheet, the tear strip extending betweeneach pair of slits and means to cut the sheet transversely at each pairof slits, thereby forming individual covers having tear strips andstarting tabs and means to apply lthese covers to a moving le ofpackages to be sealed.

Thermoplastic iilms and sheet materials are very useful for packagingmany types of commodities, one well known example being food products.One of the advantages of the use of thermoplastic materials is that heatsealing can be utilized `to fabricate and seal the packages, whetherbags, boxes, Wrapped coatings, etc. In producing satisfactory heat sealsthe proper combination of pressure, temperature and timing is veryimportant to make certain the seal is made eiectively and the packagedmaterial is not damaged. It is also important that the machinery whichforms and seals the packages is as compact and economical as isconsistent with eticient and reliable operation.

An object of this invention is to provide sealing of thermoplasticpackages.

Another object of this invention is to provide a novel method for heatsealing of thermoplastic materials.

Another `object of this invention is to provide novel heat-sealingapparatus.

Other aspects, objects and the several advantages of this invention areapparent upon study of the specification, the drawing and the appendedclaims. Y

According to my invention there is provided a method for sealingthermoplastic packages by passing a le of the packages through a sealingzone; passing a plurality of separate heat sources parallel with and4synchronized with the packages, deviating the path of the heat sourcesto move the sources into sealing engagement to seal the packages,lifting all of the heat sources as a unit and moveffective heat ICC ingthe entire group counter to the movement of the le of packages out ofcontact with the packages, and repeating the above steps to seal a groupof packages.

According to rny invention thermoplastic packages are sealed as they areconveyed through a sealing zone by a unitary assembly comprising severalsealing heads, by passing the heads in contact with a correspondingnumber ot the packages and moving the packages and the sealing headstogether through a portion of the sealing Zone in contact with eachother, moving the sealing heads out of contact with the packages bymoving the entire unit, returning the unit backward along the path ofmovement of the packages, again moving it into contact With a group ofthe packages and repeating these operations to provide a continuousoperation.

Also according to my invention, tear strip covers are provided forpackages by cutting longitudinally-spaced pairs of slits in a sheet ofcover material, heat sealing a tear strip to the sheet so that it passesbetween the slits, and then cutting the sheet transversely at the slitsto form individual covers having attached tear strips and starting tabs.i l v Further `according to my invention, there is provided a completeheat-sealing machine comprising conveying means for packages, means toapply tear strip covers as described above, and means to heat seal thecovers to the pack-ages, also as described above.

In the drawing, FIGURE 1 is a perspective view, partially diagrammatic,of a complete heat-sealing machine according to my invention.

FIGURE 2 is a diagrammatic perspective view of a portion ot thecover-applying and packaging section of the machine of FIGURE 1.

FIGURE 3 is a diagrammatic elevation illustrating the processing of thecover material and tear strip material to form and apply individual tearstrip covers to the packages.

FIGURE 4 is a perspective view of a cutter roller.

FIGURE 5 yis a perspective view of a pair of rollers used to apply atear strip to the -sheet 0f cover material.

FIGURE 6 is a perspective view of corrugated rollers used to add aresistance to deformation to the cover material.

FIGURE 7 is a perspective View of a sealer roller for the covermaterial.

FIGURE 8 isa perspective view of a package sealed according to myinvention. y

FIGURE 9 is a diagrammatic View of suitable control mechanism -forvertical displacement of sealing heads.

As illustrated in FIGURE 1, the entire machine'comprises apackage-conveying section 11, a lid-forming and applying section 12, anda sealer section 13. Conveying section 11 includes afpackage deliveryconveyor 14, a package removal conveyor 16 and a sealing sectionconveyor I7. Section 17 comprises chains 18 and 19, pairs of sprockets21 and 22j, and a plurality of package receptacles 23 supported betweenchains 18 and 19. A package-lling conduit 24- feeds the desiredcommodity into the empty packages 26. Y

As illustrated in FIGURES 1, 2 and 3, section 12 comprises support 27for supply roll 28 of cover material 81, idler rollers 29, 31 and 32,cutter roller 33, presser rollers 34, corrugating rollers 35, shearingro'ller 36 and corresponding adjustable shear bar 37, and belts 38 and39 for handling the cover material 81. Section 12 also includes asupport 4@ and supply roll 45 for tear strip maerial 82, Lguide 41,idler rollers 4Z and 43, heater 44 for handling tear strip material 82,and bringing it into contact with cover sheet material for sealingthereto. Guide 41, idler rollers 42 and 43, and air cylinder 48 aresupported on a frame 46. Heater 44 is mounted on frame 46 by pivotedsupport 47. Air cylinder 43 holds heater 44 in contact with thetearstrip material'in normal operation; but when the machine stops, thesupply of airto this cylinder isV cut off andthe spring 59 moves theheater y out of engagement withthe tear strip material to preventoverheating. Roller 49 is provided with a pivoted sup-Y port 51 and ispressed against cutter roller 33 by'weight Y 52. Belt38-travelsjoveradjustable rollers 53, 54 and 61,

belt tightenerr 56 which is biased by spring 57,*snub roll er 58 anddrive roller 59. Belt 39 travels over adjustable rollerr62, drive roller63 and belt tightener 64 which is biased by, springen. Tack-sealingmetal tapes 67 and.

to drive rollers 33, 34, 35, 36, 59 and 63 at synchronized l speeds,theremainder ofthe rollers being driven by contact with the sheetmaterialV or the driven belts. lnl operation the continuous sheet ofmaterial 31 is threaded around idler rollers 29, 3l and 32, over cutterroller 33, down between presser rollens 34 Sand corrugating rollers 35',and betweenibelts 38 and 39; A continuous strip oftearttape-material 8.2is threaded through guide 41, around idler rollers 42Mand 43, againstthe 'surface'of heater V44 andY through pressure vrollers 34. As sheetmaterial 81 passes over roller 3 3, pairs ofy closelylspaced Islits areformed' in Vthe material at intervals, the spacing of which isdeterminedby the size ofy roller, 33. Guide 41 is positioned sothatltapematerial 82 is fed .between the slits from the roller 33. Sincethis material is heated as Y it passes -overheater 44, it isy sealed tothe cover materialV asitpasses through rollers 34,:thusforming'acontinuous sheet of cover materialVv having Ya continuousv tearstrip attached'theretolongitudinally and with pairs of slits on Y eitherside of the tearystrip at spaced intervals.VV As the combined sheet andtear strip material pass through corrugating roller 35, temporarycorrugationsare formed in this material 4so that it continues Vtoytravel straightr downward even though its lower end is severed. Thecutting occurs as roller 36 rotates to bring its Ycutting blade adjacentadjustable shear bar 37.: Roller '36 is adjusted when the sealing unitvis forced downward ,against the packages to be sealed, each sealinghead 977y is pressed v against the corresponding package by the springsitilv but is permitted to adjust vertically to compensate for variationsin thickness of the packages, slight niisalignment ofthepackage,receptacles,etc.

' Preferably, a curtain in@ is provided and extends over the face ofiallof the sealing heads 97, normally slightly spaced therefrom, and heatisY supplied from the'heads to the packages through this curtain whichisV pressed in contact/withY the sealing head by Contact with thepackage. A preferred material for curtain 100 is a glass clothimpregna-ted With polytetraiiuoroethylene, but lother materialsaresuitable. For example, a polyethylene vterephthalatecurtain or alcurtain of thin heat-conductive metal can be used.k Of course, myinvention'also is applicable Vto machines ,in which no curtainisprovided and the uncovered metal sealing surfaces of the sealing headsare utilized directly. can be provided for each sealing"hea d. V In thisinstance the curtain extends across thev face of -each individualsealing head,slightly" spaced therefrorni Suitable coated ealing headscanalso be used, `for. example vheads'coated with polytetrauoroethylene.Y, i

f The use of curtain lili) prevents sticking of the material beingsealed to the sealing heads, both by reason of being Y av material whicho f itself-helps to prevent sticking and j also .because theslightly-spaced flexible curtain tends to f peel away from bothkthepackage and the sealing head on itsrshaftiso'that the shearing actionoccurs adjacent each pair df slits which Vare cutV by cutter roller 33.rIn

and 39, each coverv having .atear strip' attached thereto, and bymeansrof the slits :in the cover material a starter 1 w3 ,to the right,thus pivoting bellfcranks 83 and 8d to lower guide bar @Sand thussupport. plate: 92 and sealing tab is provided for'theztearstrip.Preferablygl'belts and 33 are driven at alinear speed'slightly greaterthan that jwith which*V the `vsheet material 81' :approaches thesebelts.V VVThus, as yeach lc'overzis severed from the continuous thismannerV individual coversjare fedjbetween belts 33",

' time rather than beingV jerked away over a large area at one An--aircylinder N2 connected with bell crank`83 by rod' w3 and clevis 194i. vCranks '83 and`84 are connected together by connecting link 1%.Sprockets 107 and 10S are pivotally supported and .sprocketsV 107 areprovided with a `mechanical Y drive. Chains m9 yextend around sprockets107 and '198 and are driven thereby; A drive lug lllislatta'ched toltrontch'ain 1h91 and to a drag Vilink 112, which alsois connected withsupport plate 92.

In the operation of the sealer sectionl3, sprockets Y107 and the' aredriveny at such a speed and chain 199Y and `drive lug'llll sorpositionedthat, as the lug lll travels along'the 'lower path ofthe chain, supportplate 92 is pulled taz-the left inVElGURE 1 along the direction oftravel ,otth'e packagesv in sealing sectionrconveyor 17, and

'4 each sealing head 97 positioneddirectly'abovethe correspondingpackage 'tobesealed .As `lug llll travels around sheet' a slight spacingloccurs between individualxcovers.` t

The'individual covers arefed frornbetween belts 38 'and 39 to the,individual packages'as they progress in package receptacles zialong thepackage-sealing section conveyor 17. Thecovers are pressed in place bysealing tape'67 v anfd768. Since heat is supplied frorn'heaters 79 and78,

through rollers76 vand 77 to fthe sealing tapeskthecovers Karle'tacksealed along two edges to the packages.

sprocket E97, air cylinderflZ is'actuated to drive rod lAsfgruidelugllll" travels around sprocketltl, air cylii'i'derlltiZisfactuatedV to` retract rod 103 and lift the entirevsealingmechanism from contact 4with .the packages.

, The entire mechanisnrthenfis drivenothe Vright and l 60 In sealer,FIGURE l, atpair of bell cranks S3 and 84: Y

areprovided withpivoted supportsfda'nd 87, respective# ly, Vand inturnrsupport 4guid-ebarttbylpivotedsupports,

Si? and 951'.'` '.A'support' plate'f92 issup'ported guide bar by means,of pairs of rollers 93' and 9d', rota-tingin brackets95andr9j6',respectively, attachedtofsupportplate 92.' `A pluralityof-individual'sealing heads 97are p o'sitioned with: respect Vtosupport'platel 92 kby bolts 99 and springsV GL'QEach sealing head97 isVprovided 'with a. y heater such'as electrical heater 91S', "a source' ofelectricall energy such/as leadf'wires 114,*and thermostatic; controlmeans suchas thermo-switch-116 Each of bolts 99'ts vcounter to thedirection of'travel of the ile of packages 1n sealing section .conveyor17.V VAriothercontrol system for cylinder M2v i'sillustrated in FIGURE9, described be1ow.-

Vlnl'tlre particular machine ,illustratefd; the distance. be' .l tweenthe vertical centerflines o f'sprocketsl7'auditie 'is equal `to thedistance spannedvby two package' pockets andtheV lineardistance aroundone of the sprockets 197 Yand' 16S is'equal'tothe linear distancespanned by a single pocket. Thus, sealing Aheads97are in Contact withthe packages to be sealedas they travelforw-ard'a distance equal'thespan of two pockets; thefpackages travel forward adistance equal to`one-halfthe spanof a pocket as the guide lug 111; travels from thelowerinost position loosely in support'pla'te` 92 and is-'attachedrigidly to the. corresponding sealing head'97. Springs lillurge the Ysealing heads 97 awayrfrom the support plate 192;, Thus,

to the uppermost position on sprocket 108; the packages travel throughtwo ,complete ypocket spans as the lug travelsbetween sprockets 10S andlili; and the packages On the other hand,'individual curtains j moveforward another one-half span as the lug traverses the distance from theuppermost point to the lowermost point of sprocket 107. Thus, from thetime sealing heads 97 are first moved out of contact with the packagesat the lowermost point of sprocket 108 until they are moved back intocontact with the packages at the lowermost point of sprocket 107, thepackages have moved forward a distance of three pocket spans, while thesealing heads have moved backward a distance of two pocket spans. Thus,the relative motion between the two is equal to tive pocket spans, andsince five sealing heads are provided on the sealer assembly eachpackage is contacted a single time. Additional contact time can beprovided by lengthening the distance between sprockets 107 and 10S andadding sealing heads. The number of sealing heads is equal to two timesthe distance between sprockets 107 and 10S plus the linear circumferenceof a single sprocket, the distance being expressed in pocket spans. fcourse, these distances should be adjusted so that a whole number ofsealing heads is used and the heads come down in register with thetraveling packages each time. The sealing operation is completelycontrolled since the temperature of the sealing heads is controlled, thespeed of travel of the packages is controlled, and the number of pocketspans for which the sealers are in contact can be regulated byadjustment of the parts of the machine.

Since all of the individual sections of the machine must besynchronized, it is preferable that the entire assembly be driven from asingle source, such as a single electric motor through non-slip drivessuch as gear trains or chains. For example, motor 141 drives chain 1S bysprocket 142. A chain 143 is driven by a sprocket (not shown) on thesame shaft -as sprockets 21, and in turn drives chain 143 and sprocket144 on the same shaft as sprockets 108. A similar drive can be providedfor lid forming and applying section 12. To simplify the description andthe drawings many details of the synchronized drive train are not shownsince such gear train and chain drives can be readily assembled byone'skilled in the art.

FIGURE 4 shows details of cutter roller 33 including a pair of cutterblades 117, adjustable for depth of cut by screw 118, and provision forradial adjustment of roller 33 for proper timing including a mountingplate 119 att-ached to roller 33 and provided with arcuate slots 121through which mounting bolts 122 are attached to drive plate 123.

FIGURE 5 shows some details of presser rollers 34 including gears 124and 12S and a spring-loaded mounting for one of the rollers, includingbearing plates 126 and 127 which are spring biased by springs 128 and129.

FIGURE 6 illustrates corrugating rollers35 and their drive gears 131 and132 showing the alternately spaced corrugating rings 133 which cause atransverse undulation or corrugation to be formed in the continuoussheet material 81 so that the loose end which occurs each time atransverse cut is made by shear roller 36 and shear bar 37 continuesvertically and is fed between belts 38 and 39 rather than possiblycurling or bending and thus interfering with the continuous operation ofthe machine.

FIGURE 7 shows shearing roller 36 and its attached shear bar 134. Thisfigure illustrates the provision for adjustment of the shear bar 37 onstationary plate 136 by means of adjusting bolts 137. Plate 136 can bemoved horizontally by screws 138 (see FIGURE 3). 1f desired, provisioncan be made to rotate roller 36 on its shaft for proper timing. f

FIGURE 8 illustrates a completed sealed Vpackage including container 146and lid 147.,V Lid 1417l includes tear strip 148 and starting tab orpull tab 149.

FIGURE 9 illustrates control mechanism for actuating air cylinder 102 atthe proper time to move support plate 92 into position for sealing justas it starts its forward movement kand to lift plate 92 from sealingposition as it reaches the forward end o f its movement. The controlmechanism comprises a three-way solenoid valve 151 and a regulator 152in air supply line 153 which is connected to a suitable source of airunder pressure (not shown). A gear box 154 is driven from some portionof the mechanism, as for example the shaft on which sprockets areattached. The output of gear box 154 is adapted to make one completerevolution for one complete revolution of lug 111. That is, the outputof gear box 154 makes one complete revolution for one completerevolution of chain 109. A rotary contactor 156 is driven by gear box154 and its sliding Contact 157 makes one complete revolution for onecomplete revolution of chain 109. An arcuate stationary contact 158 isprovided to maintain a complete circuit for the desired amount of timeduring which the sealing heads, attached to support plate 92, are pulledforward in synchronism with the traveling packages. When the Contact ismade to complete the circuit from contact 157 and contact 158 to thesolenoid 159 of valve 151, this valve is actuated to position valve 151for direct ow of air from pipe 153 to cylinder 102. When the contact isbroken, valve 151 returns to its normal position in which cylinder 102is connected with a vent 161. Cylinder 102 preferably is provided with aspring 162 to cause the mechanism to return when the air is -ventedtherefrom. Regulator 152 maintains a desired operating pressure in aircylinder 102 and can be adjusted to provide the preferred sealingpressure by the sealing heads 97 pressing against the packages to besealed. Rotary contactor 156 is provided with an arcuate slot 163 and abolt 164 so that the plate on which arcuate Contact 158 is mounted canbe rotated for ne adjustment of the timing. Alternatively, cylinder 102can be double acting, in which case suitable valving is provided toalternately pressure and vent the two sides of the piston.

As noted above, proper seal conditions are provided by controlling thelength of the contact path, requiring adjustment of the machine itself,including the distance between sprockets 107 and 108 and the number ofsealing heads on support plate 92, the speed of travel of the packagesthrough the sealing zone which, of course, is accomplished by adjustmentof the speed of the entire machine, and the temperature of the sealingheads 97. Preferably, thermoswitches 116 are adjustable to permitvariation in the temperature towhich these heads are heated. Thefcontactpressure can be adjusted by moving the lock nuts which are illustratedon bolts 99 or by replacement of springs 101 with springs having adifferent compression factor. Where desired, suitable preheating meanscan be provided for the packages or the cover film.

My invention has particular utility when applied to the sealing ofthermoplastic containers by applying thermoplastic covers and sealingthe covers to the containers, but also is applicable .to sealing othertypes of packages, for example bags which are sealed'by joining the twoedges of an open end, and wrapped objects which are sealed by joiningportions of the wrapper to itself. The sealer section 13 also can beused with other types of cover feeding apparatus. For example, in someinstances, a continuous sheet cover film is fed over the packages andthe seal formed prior to cutting the individual covers apart. Sealersection 13 also is applicable to such an operation. Lid forming andapplying section 12 also can be V used for other types of packagesealing means, although lid forming and applying section 12 and sealersection 13 when used together form a particularly desirable combinationof elements for a package-feeding machine. 1

Materials suitable for use to form the seal between the package and thecover include broadly heat-sealable materials. Of particular utility inypracticing my invention are thermoplastic materials and laminates ofthermoplastic lm. Examples of materials which can be employed includepolyethylene, which is especially well suited for sealing materials orfor use with polyethylene containers v heat is applied.

and with containers of other materials,` either heat-scalable ornonheat-sealable. My invention Ycaribe practiced utilizv ing an aluminumpackagewith. a coverlmade o-heat-sea'llaminate. Although'the bondbetweenjthe polyethylene and the' aluminum normally is not asstrong as.the bond made, for example, between Vpolyetliylene and polyethylene, itis suitable for'many types of packaging. Other types of nonheat-sealablematerial can `be used when corn-V v binedrwith a 'thermoplasticmaterial; for example, car/- board can be used to form the cover of thepackage and polyethylene, for example, ,used to Vform the seal. Forexample, a polyethylene-coated eardboard'cover can beV placed on'acardboard package 'and a suitable seal .obtained or,Y forrexamp'le, apolyethylene-coatedcardboard cover Vcan be applied to a polyethylenepackage. Thus,Y various combinations of cover and container can beutilized, -provided there is a layer of thermoplastic atjthe interfaceY' between theV cover and the container and the materials at that pointare capablerof bonding to thermoplastics when Preferably-the tear stripV82 is made ofV a material which can be heat-sealed to the cover andhave sruicie'nt strength to supply the force required to bieakthematerial of thev A particularly suitable Vmaterial is polyethylenecover. terephthalate, commercially available under the trade name MylanPreferably, this material 'is coated with a relatively Vlow softeningpointuthermoplastic suchV as polyethylene to facilitate obtaining aheatseal between the strip and the cover sheet.

Reasonable variation and modification are possibley within the scope ofmy invention whichV sets forthfmethod and apparatus for lieatsealingthermoplastic packages by conveying the packages parallelwith andsynchroniied with heat-sealing elements, applying arforce to causeheat-seal,-

' ing engagement between the packages an'd tliefelerr'ic-nts,Vv andwithdrawing Ythe elementsfas a unit Yand moving them backward along theline of travel ofthe' packages tojconi tact Vadditional packages, jnovelV cover-forming andV apply- "ing apparatus and method andpackage-sealing apparatus; Y

' passing allefof packages torbejseale'd throng-ha sealing zone; v

passing through parallel with and-.synchronized with said' iile of lpackages;

'during theparallel passage otsaidv packages-arid said y heat sources,applying'atprce1 to cause simultaneous` .i contact of. said hlev ofVsourcesY with-fa. rst group of e packages of saidpackages to Vseaksailiirst group of packages simultaneously while said packages and saidsources are in parallel movement; 1

said sealing zone separate heat sources'V Y moving said heat sourcesout. of contactlwithsaid iirst l with ajsecond group of packagesiofsaidxiilepof( pack-1 f ages to seal said'fsecond groupof packages; andrepeating the abovestepsto seal subsequent groups of packages Vin Vsaidile to effect continuous operation. 2. Amethod forsealingj'thermoplastic packages'which -comprises'z i f i a passing aiile'of packages 'to be sealed through a .seal- Y. ing zone;

passing' through said sealinr'gfione separate heat'fsrources f'. means`Vto Vmove 'said sealing. elements out of'engagecontact Vof saidsources'with a firstgroup of packagesV v of said tile of packages to seal saidfirstgroup of packages'simultaneously while. said packages and saidsources arein parallel movement;

moving said heatisources out of contact withrsaid first group ofpackagesy and l'moving nsimultaneously all of Vthem counter to themovement of said le ofv packages while, out of contact with said file ofpackages;

" againV passing all of said-heat sourcesfpa'rallel with andsynchronized with said file of packages and applying a force to causesimultaneous contact of said sources with said packageson the firstunsealed package and Vi subsequent packages; Vand repeating the abovesteps to seal each package in said ile. Y

. 3. A'r'nethodV forsealing thermoplastic packages which comprises:

passing a zone;

applying Vcovers to'saidpa'ckages; Y

passing heat Vsources through saidI sealing'zone parallel with andsynchronized withsaid ille of packages; p

during thev parallel passage .of said packages and said heat sources,applying a forcefto cause simultaneous contact ofV said-.sources'withsaid`covers to seal a firstgroup-of packages of said tile of packagessimultaneously while said packages and-said sourcesare in Vparallelmovement; i Y

Ymoving simultaneously all of said heat sources out of Y Contact with'saidfrst group of packages and. moving simultaneously all ofsaidsources while out of contact with said iile of packages'counter tothe move- Ament of said Ytile of packages; again. passing all of said heat sources parallel with and synchronized with said le of packages vandapplying a force to cause simultaneous Contact of said sources withsaidV covers'to seal af'second group of packages of said file ofpackages; and

repeatinglthe Vabove steps'to seal subsequent groups tof Ypackages insaidaiile'- to `eiect continuous operation. 4.. .Afmethod forsealingpackages which comprises:

y passing a'` ileof `packages to be sealed Vthrough a sealing zonej; n f

passing a cloverY sheet rf'paring zone; y

insaidcover preparing Zone'rotating a knife to form f a painiofclosely,spacedglongitudinal slits `in said sheetatv/regularlongitudinallyr spacedv intervals;

. Yheating av tearf strip iandrapplyingsaid strip vto said sheet 1longitudinally:thereofV extendingbetweenl saidV pairs jofslits;VV I VV,A

cuttingsaid sheet andsaidiapplied tear strip at said v pairs of slits.therebyY forming individual .package covers each'having atearstrip'anda starting tab formed by said slits; andl l applying said coversto saidpackages and sealing there- 5. A-package'sealing machine comprising:

n .meansftoconveyale. of packages to be' sealed ,along lilleV oafVpackages Vto beasealed through a sealing continuously througha cover iprea predeterminedV path; i g meansto convey vsealing elements forsaidflle of pack- ,ages parallel with and synchronizedwith' said-dile of'.packageaig' Y y .j heating means forfsaid 'sealing elements; "f l'means to'forrcersaid sealing elements simultaneously intol sealingengagement to seal a rst group .of said pack-- ages; andf Y ment withsaid first group of packages andreturnthem counter vto the movement Yofsaid file of packages outofcontact-with saidfile of packages. i

ensaere 6. Means for sealing covers to a moving tile of packagescomprising:

means to place said covers in place on said packages;

a plurality of sealing elements resiliently attached in linearrelationship to a unitary structure;

means to move said structure forward in synchronization with said iileof packages;

means to force said unitary structure toward said tile of packages tomove said sealing elements simultanea ously into sealing engagement witha irst group of said iile of said packages; and

means to move said unitary structure away from said le of packages tomove said sealing elements out of engagement with said iirst group ofpackages and to return said unitary structure to its initial position.

7. A package sealing machine comprising:

means to convey containers to be sealed in a rile along a predeterminedpath;

means to apply covers on said containers;

a plurality of sealing elements;

heating means in each of said sealing elements;

a unitary structure to support said sealing elements;

resilient mounting means to attach each of said sealing elements to saidunitary structure;

a guide bar;

means constraining movement of said unitary structure at right angles tosaid bar but permitting movement longitudinally with respect to saidbar;

means to move said structure in the direction of motion of said le ofpackages and in the opposite direction thereto;

means to move said bar toward said tile of packages when said structureis moving in the direction of movement of said tile of packages and tomove said bar away from said iile of packages when the movement of saidstructure is counter to the movement of said le of packages.

8. A package sealing machine comprising:

a conveyor to move a tile of packages to be sealed along a predeterminedpath;

means to supply a continuous sheet of cover material and to move saidmaterial continuously througha cover preparing zone;

a rotary cutter to form pairs of parallel slits in said sheet, equallyspaced longitudinally along said sheet;

means to supply a continuous tear strip;

means to heat said strip and apply it to said sheet to form a bondtherewith;

a cutter to sever said sheet and said applied strip at said pairs ofslits thereby forming a plurality of package covers having a tear stripand a starting tab therefor; and

means to apply said covers to said packages and to seal said covers tosaid packages.

9. A package sealing machine comprising:

a conveyor to move a plurality of packages to be sealed in a horizontalle;

means to apply thermoplastic covers to said packages;

means to seal said covers to said packages comprising a plurality ofsealing elements;

a heater in each of said sealing elements;

a unitary structure to support said sealing elements;

spring-biased resilient support means to attach each of said sealingelements to said unitary structure;

a horizontal guide bar;

a first pair of rollers attached to said unitary structure and engagingthe upper and lower surfaces of said bar;

a second pair of rollers attached to said unitary structure spacedhorizontally from said irst pair of rollers and contacting the upper andlower surfaces of said bar;

a pair of sprockets having their vertical center lines spacedhorizontally a distance equal to a desired amount of forward travel ofsaid sealing elements;

a chain engaging both of said sprockets and extending therebetween;

a drive pin attached to said chain;

a drag link attached to said pin and to said unitary structure;

a pair of bell cranks each having a fixed pivot axis and being pivotallyconnected with said bar at horizontally spaced intervals;

a connecting link pivotally connected With both of said bell cranks;

means to drive said sprockets in synchronism with said conveyor to movesaid sealing elements in synchronism with said packages in the directionof movement thereof and to move said sealing elements in the oppositedirection as said pin is conveyed around and between said sprockets; and

means to rotate said bell cranks to cause downward movement of saidguide bar as said unitary structure begins motion in the direction ofmovement of said packages and to move said bell cranks to raise saidguide bar as said unitary structure reaches the end of its movement inthe direction of movement of said packages and begins its reversemovement.

10. A package sealing machine comprising:

a conveyor to move a iile of packages to be sealed along a predeterminedpath continuously;

means to supply a continuous sheetof cover material continuously;

means to pass said cover material continuously over a continuouslyrunning roller having a sequence of cutters which engage the covermaterial to slit said cover material at regular intervals equally spacedlongitudinally along said material;

means to supply a continuous tear strip;

means to heat said strip and apply it to said material to form a -bondtherewith;

a cutter to sever said sheet and said applied strip at said pairs ofslits, thereby forming a plurality of package covers having a tear stripand a starting tab therefor;

means to synchronize the operation of said means to supply said covermaterial and said conveyor whereby said covers are applied to saidpackages in propel' sealing register; and

means to seal said covers to said packages.

References Cited by the Examiner UNITED STATES PATENTS 2,538,564 l/SlJensen et al 53133 X 2,638,724 5/53 Harvey 53-14 2,699,285 1/55 Bell229-51 2,815,620 l2/57 Prodigo 53-14 2,919,060 12/59 Daniels 229-5 12,958,168 11/60 Vogt 53-184 X 3,001,348 9/61 Rado 53-373 X 3,017,729 1/62 Cheeley 53--184 X FRANK E. BAILEY, Primary Examiner.

EARL I. DRUMMOND, TRAVIS S. MCGEHEE,

Examiners.

Notice of Adverse Decision in Interference In Interference N o. 95,756involving Patent N o. 3,193,978, J. Bader, HEAT SEALIN G THERMOPLASTICPACKAGES, nal judgment adverse to the patentee was rendered July 1,1968, as to claim 5.

[Oyffcffrl Gazette August 20, 1968.]

4. A METHOD FOR SEALING PACKAGES WHICH COMPRISES: PASSING A FILE OFPACKAGES TO BE SEALED THROUGH A SEALING ZONE; PASSING A COVER SHEETCONTINUOUSLY THROUGH A COVER PREPARING ZONE; IN SAID COVER PREPARINGZONE ROTATING A KNIFE TO FORM A PAIR OF CLOSELY SPACED, LONGITUDINALSLITS IN SAID SHEET AT REGULAR LONGITUDINALLY SPACED INTERVALS; HEATINGA TEAR STRIP AND APPLYING SAID STRIP TO SAID SHEET LONGITUDINALLYTHEREOF EXTENDING BETWEEN SAID PAIRS OF SLITS; CUTTING SAID SHEET ANDSAID APPLIED TEAR STRIP AT SAID PAIRS OF SLITS THEREBY FORMINGINDIVIDUAL PACKAGE COVERS EACH HAVING A TEAR STRIP AND A STARTING TABFORMED BY SAID SLITS; AND APPLYING SAID COVERS TO SAID PACKAGES ANDSEALING THERETO.